Traffic jams are the cause of approximately 25 billion euro of annual expenses of the state of Germany [14, 26]. In addition to these monetary damages they also have a negative effect on the quality of life for man and nature. They are, for example, the source of a non-negligible part of the 2.4 billion traffic accidents with damage of property or persons registered annually [13]. Circa 14 % of crashes result from previous mishaps [8, 26]. Almost all of them cause further jam formation and therefore a vicious circle which is in danger of closing around. Especially jams being created from spontaneous, non-periodic incidents involve a high risk of ending in a gridlock and thereby disrupt a whole traffic system. Because these disturbances are unpredictable and unpreventable, their duration and impact can merely be reduced by an effective incident management through the systematic, planned and coordinated use of institutional, technical and natural resources. The self-healing-network-strategy by Lämmer [19] and Rausch [27] is one example of such a countermeasure against jam formation in urban road networks. It prevents gridlocks at intersections by means of traffic lights and the combination of two effective mechanisms. Extended off-times prevent the inflow into oversaturated sections and so the expansion of tailbacks onto upstream intersections. Extended green periods of alternative directions of travel motivate drivers to avoid disturbed sectors and thus additionally allow a better exploitation of available free capacities. The development and successful establishment of this method could make the use of ramp metering in urban networks - which is regulating the inflow of oversaturated areas by reducing or skipping green times as well - invalid. To answer this question the presented master’s thesis aims at comparing both inflow-regulating control concepts. However, it is not the ambition to proof that one method is worse than the other, but to contribute to an ideal combination of both instead - with the intention to eliminate deficits on either side. Therefore both concepts will be reviewed in a first step and subsequently the contribution of additional effects against gridlock creation through the symbiosis of the two traffic light controls is analysed. Furthermore, several suggestions for the development of an efficient ramp metering logic are introduced to configure this combination to be more beneficial.:1 Einleitung 1.1 Sinngebung und Relevanz dieser Untersuchung 1.1.1 Entstehung von Verkehrsstörfällen und Staubildung 1.1.2 Extremfall Gridlock 1.2 Vorgehensweise und erwartete Ergebnisse 2 Theoretische Grundlagen 2.1 Allgemeine Verkehrskenngrößen 2.2 Lichtsignalanlagen 3 Lichtsignalanlagen und andere Steuerungskonzepte der Verkehrstelematik 3.1 Grundkonzepte der Verkehrstelematik zur Verkehrsbeeinflussung 3.1.1 Informationssysteme 3.1.2 Streckenbeeinflussungsanlagen 3.1.3 Netzbeeinflussungsanlagen 3.1.4 Knotenpunktbeeinflussungsanlagen 3.2 Lichtsignalanlagen 3.2.1 Steuerungsebenen 3.2.2 Urban Traffic Control 3.3 Rückstauregulierung durch ein selbstorganisiertes Störfallmanagement 3.3.1 Staufrontkontrolle durch Zuflussdosierung 3.3.2 Kapazitätsausschöpfung durch Umverteilung der Verkehrsströme 3.3.3 Vorzüge und Defizite 3.4 Pförtnerung 3.4.1 Ziele einer erfolgreichen Zuflussdosierung mithilfe einer PA 3.4.2 Anforderungen an Pförtneranlagen 3.4.3 Steuerung der Pförtneranlage 4 Modellierung und Simulation 4.1 Netzwerkmodellierung 4.1.1 Struktur des Straßennetzes 4.1.2 Knotenpunkte 4.1.3 Dimensionierung der LSA 4.2 Implementierung der Rückstauregulierung 4.2.1 Bemessung der Rückstaulänge 4.2.2 Schätzung der Staukapazität 4.2.3 Bemessung der Freigabezeit 4.2.4 Umsetzung in einem Straßennetzwerk 4.3 Implementierung der PA-Steuerung 4.3.1 Festzeitsteuerung 4.3.2 Verkehrsabhängige Bestandteile zur Zuflussdosierung 4.3.3 Unzulässigkeit der Verkehrsstärke als Auslösekriterium 4.3.4 Variation des Bemessungshorizonts der Auslösekriterien 4.4 Dynamisches Routenwahlverhalten der Fahrer 4.5 Szenariomodellierung und Simulationsergebnisse 4.5.1 Bewertung der Effizienz der Steuerungskonzepte zur Gridlock- Prävention 4.5.2 Simulationsszenarien für Störfälle 5 Fazit und Ausblick 5.1 Zusammenfassung 5.2 Diskussion der Ergebnisse 5.2.1 Effizienz des ereignisorientierten Routenwahlmodells und selbstorganisierten Störfallmanagements 5.2.2 Effizienz der Pförtnersteuerung zur Isolation des sensiblen gestörten Areals 5.2.3 Ausblick und Bewertung der Simulationen 5.3 Vorschlag zur Aufrechterhaltung eines minimalen Verkehrsflusses während der Dosierung durch PA / Verkehrsstaus verursachen dem deutschen Staat jährlich rund 25 Milliarden Euro Unkosten [14, 26]. Neben diesen monetären Schäden wirken sie sich jedoch auch negativ auf die Lebensqualität von Mensch und Umwelt aus. Sie sind beispielsweise die Ursache für einen nicht unerheblichen Anteil der circa 2,4 Milliarden jährlich registrierten Unfälle mit Sach- oder Personenschaden [13]. Rund 14 % der Unglücksfälle gehen dabei als Folgeerscheinung eines vorherigen Unfalls hervor [8, 26]. Nahezu alle führen eine weitere Staubildung herbei und somit einen Teufelskreis, der sich zu schließen droht. Besonders aus spontanen, nicht wiederkehrenden Störfällen entstandene Staubildung birgt eine hohes Risiko, in einem Gridlock zu enden und damit ein gesamtes innerstädtisches Verkehrssystem zum Erliegen zu bringen. Da diese Störfälle unvorhersehbar und unvermeidbar sind, kann ihrer Dauer und ihrem Einfluss lediglich ein effizientes Störfallmanagement durch systematischen, gezielten und koordinierten Gebrauch institutioneller, technischer und natürlicher Ressourcen entgegenwirken. Beispiel für eine solche Gegenmaßnahme zur Staubildung in urbanen Netzen ist das selbstorganisierte Störfallmanagement nach Lämmer [19] und Rausch [27]. Mithilfe von LSA und der Kombination zweier effektiver Wirkungsmechanismen werden Gridlocks an Knotenpunkten unterbunden. Verlängerte Sperrzeiten verhindern den Zufluss in übersättigte Streckenabschnitte und damit die Ausbreitung von Rückstaus auf vorgelagerte Kreuzungen. Erweiterte Freigabezeiten der alternativen Fahrtrichtungen regen wiederum eine Umgehung des gestörten Abschnitts an und ermöglichen somit zusätzlich die bessere Ausschöpfung vorhandener freier Kapazitäten. Durch die Entwicklung und den erfolgreichen Einsatz der genannten Maßnahme könnte der Gebrauch von Pförtnerampeln (PA), welche den Zufluss in übersättigte Bereiche ebenfalls regulieren, indem sie Grünzeiten verkürzen oder aussetzen, hinfällig werden. Um diese Frage zu klären, widmet sich die vorliegende Masterarbeit dem Vergleich der beiden zuflussregulierenden Steuerungskonzepte. Ziel ist jedoch nicht, zu beweisen, dass eine Maßnahme schlechter ist als die andere, sondern vielmehr einen Beitrag zu einer optimalen Kombination der Vorzüge beider Herangehensweisen zu leisten und somit die auf beiden Seiten vorhandenen Defizite zu beseitigen. Dafür werden zunächst beide Konzepte auf ihre Effizienz hin überprüft und im Anschluss analysiert, inwiefern die Symbiose beider LSA-Steuerungen in einem Netzwerk zusätzliche Effekte gegen die Gridlockentstehung bewirkt. Außerdem werden verschiedene Vorschläge zur Entwicklung einer effizienteren Steuerlogik für Pförtneranlagen eingebracht, um diese Kombination noch vorteilhafter zu gestalten.:1 Einleitung 1.1 Sinngebung und Relevanz dieser Untersuchung 1.1.1 Entstehung von Verkehrsstörfällen und Staubildung 1.1.2 Extremfall Gridlock 1.2 Vorgehensweise und erwartete Ergebnisse 2 Theoretische Grundlagen 2.1 Allgemeine Verkehrskenngrößen 2.2 Lichtsignalanlagen 3 Lichtsignalanlagen und andere Steuerungskonzepte der Verkehrstelematik 3.1 Grundkonzepte der Verkehrstelematik zur Verkehrsbeeinflussung 3.1.1 Informationssysteme 3.1.2 Streckenbeeinflussungsanlagen 3.1.3 Netzbeeinflussungsanlagen 3.1.4 Knotenpunktbeeinflussungsanlagen 3.2 Lichtsignalanlagen 3.2.1 Steuerungsebenen 3.2.2 Urban Traffic Control 3.3 Rückstauregulierung durch ein selbstorganisiertes Störfallmanagement 3.3.1 Staufrontkontrolle durch Zuflussdosierung 3.3.2 Kapazitätsausschöpfung durch Umverteilung der Verkehrsströme 3.3.3 Vorzüge und Defizite 3.4 Pförtnerung 3.4.1 Ziele einer erfolgreichen Zuflussdosierung mithilfe einer PA 3.4.2 Anforderungen an Pförtneranlagen 3.4.3 Steuerung der Pförtneranlage 4 Modellierung und Simulation 4.1 Netzwerkmodellierung 4.1.1 Struktur des Straßennetzes 4.1.2 Knotenpunkte 4.1.3 Dimensionierung der LSA 4.2 Implementierung der Rückstauregulierung 4.2.1 Bemessung der Rückstaulänge 4.2.2 Schätzung der Staukapazität 4.2.3 Bemessung der Freigabezeit 4.2.4 Umsetzung in einem Straßennetzwerk 4.3 Implementierung der PA-Steuerung 4.3.1 Festzeitsteuerung 4.3.2 Verkehrsabhängige Bestandteile zur Zuflussdosierung 4.3.3 Unzulässigkeit der Verkehrsstärke als Auslösekriterium 4.3.4 Variation des Bemessungshorizonts der Auslösekriterien 4.4 Dynamisches Routenwahlverhalten der Fahrer 4.5 Szenariomodellierung und Simulationsergebnisse 4.5.1 Bewertung der Effizienz der Steuerungskonzepte zur Gridlock- Prävention 4.5.2 Simulationsszenarien für Störfälle 5 Fazit und Ausblick 5.1 Zusammenfassung 5.2 Diskussion der Ergebnisse 5.2.1 Effizienz des ereignisorientierten Routenwahlmodells und selbstorganisierten Störfallmanagements 5.2.2 Effizienz der Pförtnersteuerung zur Isolation des sensiblen gestörten Areals 5.2.3 Ausblick und Bewertung der Simulationen 5.3 Vorschlag zur Aufrechterhaltung eines minimalen Verkehrsflusses während der Dosierung durch PA

This study assesses the phenomenon of additional water intruding into sewage sys-tems in different areas of Sweden. Additional water means in this case the non-foul water that can originate from storm water runoff, which is either supposed to be con-veyed into the pipe system or intrudes it by wrongly connected drains. It can also re-sult from in-seepage of groundwater due to imperfections of the pipe system itself. It is intended to analyze how different features of the areas have an impact on the extent of this phenomenon. Further, an estimation of the conditions in future scenarios will be obtained. This includes an indication about the potential risk of a sewage system overflow, the expected volume of inflow at treatment plants and thus about the sys-tem´s suitability for the future. Numerical, hydrological compartment models for 19 cities in Sweden were set-up. The used parameters were obtained from previous studies by the Swedish Environ-mental Protection Agency. In these models present and future climate data were ap-plied. For future scenarios three different climate change projections were used which contain bias corrected climate data timeseries for each study area. The climate change scenarios were supposed to represent an "optimistic", "average" and "pessimistic" outlook. By assessing the outputs of the climate models, it was concluded that signifi-cant differences can occur, depending on exact geographical location and chosen cli-mate models. A sensitivity analysis was conducted of how geology, climate and status of the pipe system have an impact on the extent of additional water flows. It revealed that the status of the sewage system has by far the biggest impact. Finally a discharge analysis showed a potential outlook of future development of additional water flows for the chosen study sites, yielding highest increase for the sewage systems of Kiruna, Karlskoga and Sundsvall.

As drivers of biogeochemical cycles and nutrient recycling, such as carbon turnover, the microbial community is essential in sustaining functioning ecosystems. Together with the metazoan community, the microbial community constitute the majority of all life in the benthos. Environmental change in biotic and abiotic factors may influence the dynamics of these communities, for example through a sorting or driving effect on the community structure through assembly processes. Environmental change, e.g. change in dissolved oxygen concentration, salinity and temperature, can directly or indirectly affect community composition. How, in what way, and to what extent, benthic bacterial and meiofaunal community composition in the eutrophied, brackish benthic environments, in the Baltic Sea sub-basin the Baltic Proper, respond to environmental change is understudied, both at local and seascape scale. This thesis aimed to study and understand the effects of environmental variation on the diversity and biogeographic patterns of Baltic Sea sediment bacterial and meiofaunal communities. A further aim was to understand the links between the different community levels by studying the interaction between meiofaunal- and macrofaunal communities in relation to environmental variation. Community diversity was analysed along a latitudinal transect of national environmental monitoring stations in the Baltic Proper using a framework of metapopulation and metacommunity theory. The analyses were based on environmental genomics, with high-throughput sequencing, bioinformatics and statistics. The total community genome was analysed using phylogenetic marker gene fragments as a proxy for taxonomic diversity, to investigate diversity, community structure and dynamics. Salinity and oxygen were found to be the main abiotic environmental drivers of benthic community composition and alpha- and beta-diversity patterns. Furthermore, macrofauna-meiofauna interactions were significantly more complex in higher salinity environments. Results also showed that both enhanced environmental gradients and dispersal following a major inflow of saline and oxygenated water from the Atlantic Ocean, influenced the composition of sediment bacterial communities at the seascape scale of the Baltic Sea, as shown by a reduced beta-diversity and increased alpha-diversity, and the development of a significant distance-decay of community similarity. This study also identified strong metapopulation dynamics of the benthic sediment bacterial communities with many satellite and a few core taxa. The outcomes from this study contribute to the understanding of how environmental variation and environmental change relate to changes in Baltic Sea benthic community diversity and composition, and important factors and processes governing community dynamics.

Thesis is aimed on creation of prediction model for releasing medium-term water stream flow forecasts. Created model create forecasts based on principal of finding most similar historical case. Usefulness of forecasting model is demonstrated for operation of one isolated reservoir in gauge profile Oslavany on river Oslava.

To simulate a hydropower system, one can use what is known as a Detailed model. However, due to the complexity of river systems, this is often a computationally heavy task. Equivalent models, which aim to reproduce the result of a Detailed model, are used to significantly reduce the computation time for these simulations. This thesis attempts to compute Equivalent models for hydropower systems in Sweden by categorizing the inflow data using a spectral clustering method. Computing the Equivalent models also involves solving a bilevel optimization problem, which is done using a variant of the particle swarm optimization algorithm. Equivalent models are computed for all four electricity trading areas in Sweden, using solutions of a Detailed model which includes ten rivers. Then, the Equivalent models are evaluated based on their similarity to the Detailed model in terms of power production and objective value. The results vary depending on the area and period, and the Equivalent models range from 8% - 15% error in terms of the relative power production difference. The results indicate that the inflow clustering procedure produces adequate Equivalent models in most cases. / För att simulera ett vattenkraftsystem, kan en så kallad Detaljerad modell användas. På grund av komplexiteten av flodsystem, kan lösningen av en Detaljerad modell ta mycket lång tid att hitta. Ekvivalenta modeller, som strävar att efterlikna en Detaljerad modell, används för att reducera lösningstiden markant. Denna avhandling försöker beräkna Ekvivalenta modeller för vattenkraftsystem i Sverige genom att kategorisera inflödesdata med hjälp av en spektral klustringsmetod. Beräkningen av de Ekvivalenta modellerna involverar att lösa ett så kallat bilevelproblem, vilket görs med en variant av particle swarm optimization. Ekvivalenta modeller beräknas för alla fyra elområden i Sverige, baserad på lösningar av en Detaljerad modell som inkluderar tio floder. Sedan utvärderas de Ekvivalenta modellerna efter hur mycket de liknar den Detaljerade modellens kraftproduktion samt objektivvärde. Resultaten varierar beroende på elområde och period, och de Ekvivalenta modellerna har fel på 8% - 15% i den relativa kraftproduktionsskillnaden. Resultaten indikerar att metoden att klustra efter inflöde ger tilfredsställande Ekvivalenta modeller i de flesta fallen.

The failure of sewer pipes is a significant issue that can adversely affect the environment and public health. The problem is exacerbated by the additional burden it places on treatment plants, which must work harder to process the increased sewage flow resulting from pipe failures. The research in this thesis is based on an extensive review of the existing literature on sewer pipe failure and inspection, focusing on the proactive approach that can predict pipe failures to assist in effective maintenance. The study finds that several predictive models can accurately predict sewer deterioration with high accuracy (up to 95 % precision), making it possible to identify potential failures and address them before they cause significant damage or disruption. However, the research indicates that there has been relatively little work done on predicting blockage and CSO, two critical aspects of sewer pipe management that could be addressed more to manage sewer systems effectively. The thesis discusses that by developing an effective predictive model for prioritisation of monitoring sewer pipes, planners can save time and money on individual inspections while planning well ahead to avoid any service disruption. The study also summarised the data needs for the predictive models and found pipe age, material, diameter depth, and length to be the most commonly used input parameters by the existing model developers. The finding of this research can guide decision support in future efforts to improve sewer pipe inspection practices. / Fel på avloppsrör är en viktig fråga som kan påverka miljön och folkhälsan negativt. Problemet förvärras av den extra börda det innebär för reningsverken, som måste arbeta hårdare för att hantera det ökade avfallsflödet till följd av rörbrott. Forskningen i denna avhandling baseras på en omfattande genomgång av den befintliga litteraturen om fel på avloppsrör och inspektion, med fokus på det proaktiva tillvägagångssättet som kan förutsäga rörfel för att bidra till effektivt underhåll. Studien visar att flera prediktiva modeller kan förutsäga försämring av avlopp med hög noggrannhet (upp till 95 % precision), vilket gör det möjligt att identifiera potentiella fel och åtgärda dem innan de orsakar betydande skador eller störningar. Forskningen visar dock att det har gjorts relativt lite arbete för att förutsäga blockering och CSO, två kritiska aspekter av hantering av avloppsrör som skulle kunna hanteras mer för att hantera avloppssystemet effektivt. I avhandlingen diskuteras att genom att utveckla en effektiv prediktiv modell för prioritering av övervakning av avloppsrör kan planerare spara tid och pengar på enskilda inspektioner och samtidigt planera i god tid för att undvika eventuella driftstörningar. Studien sammanfattade även data behovet för de prediktiva modellerna och fann att röra ålder, material, diameter, djup och längd var de mest använda ingångs parametrarna av de befintliga modellutvecklare. Resultatet av denna forskning kan vägleda beslutsstöd i framtida ansträngningar för att förbättra praxis för inspektion av avloppsrör.

The aim of this thesis was to evaluate the validity of statistical modelling, with regards to flow in wastewater systems based on precipitation. A wastewater system, which is a system of pump-stations connected via pipes, is affected by precipitation as rainwater enters the system. The rainwater that enters the system can sometimes, especially if the precipitation is heavy, increase the flow by several hundred percent. The goal with the models created for this report was, to first predict how much rainwater there was in the wastewater system based on precipitation, and second, to examine where in a geographical grid this rainwater entered the system. For the first goal a linear regression model was applied, this model showed that it was indeed possible to predict excess water in the system, but large errors for individual time points where to be expected, especially for light precipitation. For the second goal a random forest model was applied. This model however gave no additional insight beyond what an initial correlation study between precipitation in different parts of the geographical grid and flow had already shown. The areas in the geographical grid pointed out by both the random forest model and the initial correlation study were not the actual uptake areas of the pump-station these models were applied to. This leads to the conclusion that for the data set used, and with the models applied in the manner in which they were in this thesis, it was not possible to predict where rainwater enters the system. / Målet med den här rapporten var att undersöka möjligheten att modellera regnvattens påverkan på vattenflödet i avloppsystem, med statistiska modeller. Ett avloppsystem är i dess enklaste form ett nätverk av pumpstationer sammanbunda med rör. Det här systemen påverkas av nederbörd då oönskat regnvatten kommer in via stuprör, avloppsbrunnar och sprickor i rören. Regnvattnet kan i vissa fall, särskilt under perioder med mycket nederbörd, öka flödet i avloppsystemet med flera hundra procent. Modellerna tillverkade för den här rapporten undersökte två olika aspekter av regnvattnets påverkan: Kan flöde i avloppssystemet modelleras med regnvatten? Och kan modellerna avgöra var regnvatten kommer in i avloppsystemet? Den första frågan undersöktes med linjär regressionsanalys, modellerna tillverkade med regression visade att det gick att modellera flöde i avloppsystemet med regnvatten, det bör dock nämnas att stora fel i enskilda tidssteg var att förvänta, speciellt för modellering då nederbörden är låg. Den andra frågan utvärderades med en ”random forest” modell. Den här modellen gav ingen ytterligare information angående var regnvatten kommer in i systemet, utöver vad som redan hade visats av en korrelationsstudie gjord i början av projektet. Både korrelationsstudien och ”random forest” modellen visade också på att regnvattnet kom från platser som inte var sammankopplade med den pumpstation testerna gjordes på. På grund av detta drogs slutsatsen att det inte gick att ta reda på var regnvattnet kommer in i systemet, med den data som använts, och på det sätt som modellerna har använts i den här rapporten.

Inflow and infiltration (I/I) water in the sewer network originates from groundwater, precipitation, seawater as well as over-leakage from drinking water pipes. It is the proportion of water in the sewer system that is not wastewater and causes problems both at the treatment plant as well as in the sewer network. Through overflows, floods and bypassing at the treatment plant I/I causes discharges of wastewater to recipients and nature and thus have negative environmental effects. I/I also stand for an overload in the system which, in addition to environmental consequences, also has social, economic and technical consequences. Despite efforts to reduce and mitigate the effects of I/I water for a long time, the problem remains and a large proportion of all the wastewater in the network and the treatment plan still is I/I.  Historically, and for many cases at present, there is little to no methodology for how the work with I/I water takes place and is prioritized in the municipalities and responsible water and sewerage organizations. Measures have instead been implemented with a reaction based approach, in other words when something has broken down or there is a failure in the system. A new discussion about I/I water has arisen in recent years due to new requirements from supervisory authorities. As there is not much follow-up or methodology around the work with I/I water, the process of developing a strategy to meet these new requirements for municipalities has shown to be difficult. In cases where analysis of measures against I/I water has been carried out, cost and effects in the treatment plant (i.e. the proportion of I/I water) have most often been used and dimensions other than economic have been left out of the analysis. As I/I water affects social and environmental factors to a great extent, this should be taken into greater account.  In this work, a multi-criterion analysis has been performed in a case study where similar measures to reduce I/I water and its effects in two different areas have been analysed. The included measures were separation, lining, pipe bursting and installation of a stormwater cassette. The results of the case study show that measure A2 has the greatest positive effect. However, there are major uncertainties in the case study conducted and the results are not considered to be robust enough to be used. However, what has been important to include from the work is that by defining and using criteria from all sustainability dimensions, a comprehensive action choice analysis is created and that it is a structured approach to apply. Here, the importance of opening up for discussion within the municipality/organization is emphasized to achieve a coherent view of the prioritization of I/I water and to achieve efficient management. Problems and amounts of I/I water are complex issues and vary from place to place, and are strongly linked to local geohydrological and climate conditions and design of local sewage systems. Therefore, it is important to coordinate the planning of I/I water to use a workflow that is general and can be used, regardless of conditions, in a simple way where adjustments in accordance with local conditions are possible. This work has shown that multi-criteria analysis is a clear and adaptable tool for meeting the difficulties that exist. / Tillskottsvatten härstammar från grundvatten, nederbörd samt havsvatten genom felaktiga anslutningar eller läckage i ledningsnätet samt från överläckage från dricksvattenledningar. Det är andelen av vatten i avloppsnätet som inte är spillvatten och orsakar, genom bräddning, översvämningar och förbiledning i reningsverket, utsläpp av avloppsvatten till recipienter och natur samt står för en överbelastning i systemet. Trots att man arbetat med att minska och lindra effekterna av tillskottsvatten under lång tid så kvarstår problemet och en stor andel av allt samlat vatten i ledningsnätet och som kommer till reningsverket är just tillskottsvatten.  Historiskt, samt för många fall i nuläget, så existerar det lite till ingen metodik kring hur arbetet med tillskottsvatten sker i kommunerna och ansvariga VA-organisationer utan åtgärder har implementerats på måfå eller när något har gått sönder. En ny diskussion kring tillskottsvatten har uppstått de senaste åren på grund av uppkomna nya kravställningar från tillsynsmyndigheter. I och med att det inte finns mycket uppföljning eller metodik kring arbetet med tillskottsvatten så har processen med att ta fram en strategi för att möta dessa nya krav för kommuner ofta varit svår. I de fall som analys av åtgärder mot tillskottsvatten har utförts så har kostnad och effekter i reningsverket (det vill säga andel mängd tillskottsvatten) oftast används och andra dimensioner än ekonomiska har lämnats utanför analysen. Då tillskottsvatten påverkar sociala samt miljömässiga faktorer i hög grad bör detta tas större hänsyn till.  I det här arbetet så har en multikriterieanalys utförts i en fallstudie där liknande åtgärder för att minska tillskottsvatten och dess effekter i olika områden har analyserats. De ingående åtgärderna var separering, infodring, rörspräckning samt anläggning av en dagvattenkassett. Resultatet av fallstudien visar att åtgärdsalternativ 2 har störst positiv effekt. Det finns dock stora osäkerheter i den fallstudie som utförts och resultatet anses inte vara tillräckligt robust för att användas. Det som dock har varit viktigt att ta med från arbetet är att genom att definiera och använda kriterier från alla hållbarhetsdimensioner skapas en heltäckande åtgärdsvalsanalys och att det är ett strukturerat arbetssätt att applicera. Här understryks vikten av att öppna upp för diskussion inom kommunen/organisationen för att nå en sammanhållen syn på prioriteringen av tillskottsvatten samt för att nå en effektiv hantering. Problem och mängder tillskottsvatten i olika ställen är komplext och starkt kopplat till lokala klimat och geohydrologiska förhållanden samt lokala avloppssystem. Därför är det viktigt för att samordna planeringen av tillskottsvatten att använda en arbetsgång som är generell och kan användas, oavsett förutsättningar, på ett enkelt sätt där justeringar i enlighet med lokala förutsättningar är möjligt. Det här arbetet har visat att multikriterieanalys är ett tydligt och anpassningsbart verktyg för att möta de svårigheter som finns.

The primary goal of this research is to evaluate and identify proper calibration approaches, skillful hydrological models, and suitable weather forecast inputs to improve the accuracy and reliability of hydrological forecasting in different types of watersheds. The research started by formulating an approach that examined single- and multi-site, and single- and multi-objective optimization methods for calibrating an event-based hydrological model to improve flood prediction in a semi-urban catchment. Then it assessed whether reservoir inflow in a large complex watershed could be accurately and reliably forecasted by simple lumped, medium-level distributed, or advanced land-surface based hydrological models. Then it is followed by a comparison of multiple combinations of hydrological models and weather forecast inputs to identify the best possible model-input integration for an enhanced short-range flood forecasting in a semi-urban catchment. In the end, Numerical Weather Predictions (NWPs) with different spatial and temporal resolutions were evaluated across Canada’s varied geographical environments to find candidate precipitation input products for improved flood forecasting. Results indicated that aggregating the objective functions across multiple sites into a single objective function provided better representative parameter sets of a semi-distributed hydrological model for an enhanced peak flow simulation. Proficient lumped hydrological models with proper forecast inputs appeared to show better hydrological forecast performance than distributed and land-surface models in two distinct watersheds. For example, forcing the simple lumped model (SACSMA) with bias-corrected ensemble inputs offered a reliable reservoir inflow forecast in a sizeable complex Prairie watershed; and a combination of the lumped model (MACHBV) with the high-resolution weather forecast input (HRDPS) provided skillful and economically viable short-term flood forecasts in a small semi-urban catchment. The comprehensive verification has identified low-resolution NWPs (GEFSv2 and GFS) over Western and Central parts of Canada and high-resolution NWPs (HRRR and HRDPS) in Southern Ontario regions that have a promising potential for forecasting the timing, intensity, and volume of floods. / Thesis / Doctor of Philosophy (PhD) / Accurate hydrological models and inputs play essential roles in creating a successful flood forecasting and early warning system. The main objective of this research is to identify adequately calibrated hydrological models and skillful weather forecast inputs to improve the accuracy of hydrological forecasting in various watershed landscapes. The key contributions include: (1) A finding that a combination of efficient optimization tools with a series of calibration steps is essential in obtaining representative parameters sets of hydrological models; (2) Simple lumped hydrological models, if used appropriately, can provide accurate and reliable hydrological forecasts in different watershed types, besides being computationally efficient; and (3) Candidate weather forecast products identified in Canada’s diverse geographical regions can be used as inputs to hydrological models for improved flood forecasting. The findings from this thesis are expected to benefit hydrological forecasting centers and researchers working on model and input improvements.

The effectiveness of South Africa's policy framework towards attracting FDI has been questionable. Determined to redress the instabilities created by the apartheid regime, the Government of National Unity (GNU) commissioned the Macroeconomic and Research Group (MERG), and charged it to devise appropriate policy reforms and intervention mechanism to address the shortcomings. This research critically interrogates the effectiveness of government's policy reforms towards attracting FDI, especially the impacts of the Reconstruction and Development Programme (RDP), the Growth, Employment and Redistribution (GEAR) initiative and the Accelerated and Shared Growth Initiative of South Africa (ASGISA). This research concludes that the policy determinants for inflow FDI have been self-defeating. Also, it was found that necessary reforms would have to be conducted to correct some of the shortcomings of the macroeconomic policies, as a way of creating an environment that is capable of attracting greenfield investments (FDI) to South Africa. / Business Management / M. Com. (Business Management)